Normal Chilled Water (WC) Flashcards
What supplementary loads does WC cool?
Non nuclear process sampling coolers
Polishing demins
Blowdown demins
Main generator collector housing
What buildings are cooled by the WC system during all modes of normal operation?
Containment, control, aux, and radwaste buildings
What is the maximum number of chiller allowed to be running at a given time?
2 of 3 large and the one small
What are the three most critical loads cooled by the WC system?
Ctmt norm AHUs
CEDM Control Cabinet room
Generator collector housing cooler
What interlock do the containment normal ACUs have?
When the fan is not running the isolation valve for the chilled water closes.
What provides cooling water for chillers A, B, C, and e02?
NC
What is the power supply to the A chiller compressor?
PB
What system provides makeup water for the chilled water expansion tank?
DW
What provides a 75 psig overpressure for the chilled water expansion tank?
GA nitrogen, or hydrogen if needed
What system provides power to the WC circulation pumps?
NH
What is the power supply to the B, C, and e02 chiller compressors?
NB
Where does the waste drains/vents go once collected by the CM system?
Chem waste neut tank
Describe the start up sequence when the chiller switch is taken to START.
The CW circ pump starts along with the oil pump
The compressor starts after a delay to allow oil pressure to rise and circulation to start.
Describe the sequence of events when the chiller switch is taken to STOP.
The CW circ pumps stops immediately with the compressor.
The oil pump continues to run on a time delayed stop to allow the compressor to coast down
How is the N2 cover gas in the chilled water expansion tank added?
Automatically to maintain 75 psig for NPSH.
How are chemical added to the system once introduced to the pot feeder?
The dP from the running WC pumps draws the chemicals in. Only one chemical may be added at a time.
What three components add to the efficiency of the normal chillers?
Integral thermal economizer
Flash economizer
Two stage compressor
What does the integral flash economizer do?
Sub cools the refrigerant
What does the flash economizer do?
Increases the proportion of liquid refrigerant in the cooler which will lead to an increase in heat transfer.
What is the purpose of the purpose of having a two stage compressor?
Decreases the required work of compressor, which increases efficiency.
What causes surging and what do we use to prevent it?
Pressure of refrigerant in the condenser is higher than at the compressor discharge.
Use the hot gas bypass
Describe stacking and what we use to prevent it.
Occurs during low loads
Hot gasses condense at too high of a rate and refrigerant “stacks” up in the condenser.
Refrigerant head pressure control valve
How long must we wait to restart a chiller if started recently?
20 minutes
How long must we wait to restart the chiller if it has tripped recently.
15 minutes.
What ESFAS signal causes the motor operated isolation valves outside containment to close automatically.
CIAS
How is cooling modulated for each individual ACU/AHU?
Chilled water flow is modulated by a three way temperature control valve.
Flow is directed to the heat load or a bypass line.
How is makeup water to the WC system added?
Automatically to the expansion tank as sensed by LV-16
What happens to the isolation valves to the radwaste/control building (UV-70), aux building (UV-71) headers on loss of IA?
They all fail closed
What happens to the temperature control valves on a loss of IA?
The fail open to full cooling.
What happens to the running chillers on a loss of NC?
The running normal chillers will trip and EW will take over to cool the “priority loads”
What ESFAS signal will trip the A chiller package if it is running following a LOOP?
SIAS
What happens to the WC flow upon receipt of a CIAS?
The WC flow to the ctmt normal ACUs is isolated.
